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Approximation algorithm

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388:), complex data structures, or sophisticated algorithmic techniques, leading to difficult implementation issues or improved running time performance (over exact algorithms) only on impractically large inputs. Implementation and running time issues aside, the guarantees provided by approximation algorithms may themselves not be strong enough to justify their consideration in practice. Despite their inability to be used "out of the box" in practical applications, the ideas and insights behind the design of such algorithms can often be incorporated in other ways in practical algorithms. In this way, the study of even very expensive algorithms is not a completely theoretical pursuit as they can yield valuable insights. 73:. The field of approximation algorithms, therefore, tries to understand how closely it is possible to approximate optimal solutions to such problems in polynomial time. In an overwhelming majority of the cases, the guarantee of such algorithms is a multiplicative one expressed as an approximation ratio or approximation factor i.e., the optimal solution is always guaranteed to be within a (predetermined) multiplicative factor of the returned solution. However, there are also many approximation algorithms that provide an additive guarantee on the quality of the returned solution. A notable example of an approximation algorithm that provides 3210: 4252: 330:. In the case of the metric traveling salesman problem, the best known inapproximability result rules out algorithms with an approximation ratio less than 123/122 ≈ 1.008196 unless P = NP, Karpinski, Lampis, Schmied. Coupled with the knowledge of the existence of Christofides' 1.5 approximation algorithm, this tells us that the threshold of approximability for metric traveling salesman (if it exists) is somewhere between 123/122 and 1.5. 1629: 144:
problem, where the goal is to choose the smallest set of vertices such that every edge in the input graph contains at least one chosen vertex. One way to find a vertex cover is to repeat the following process: find an uncovered edge, add both its endpoints to the cover, and remove all edges incident
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to better understand the limits to which we can approximate certain famous optimization problems. For example, one of the long-standing open questions in computer science is to determine whether there is an algorithm that outperforms the 2-approximation for the Steiner Forest problem by Agrawal et
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al. The desire to understand hard optimization problems from the perspective of approximability is motivated by the discovery of surprising mathematical connections and broadly applicable techniques to design algorithms for hard optimization problems. One well-known example of the former is the
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to find a vertex cover that is at most twice the value of the relaxation. Since the value of the relaxation is never larger than the size of the optimal vertex cover, this yields another 2-approximation algorithm. While this is similar to the a priori guarantee of the previous approximation
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While inapproximability results have been proved since the 1970s, such results were obtained by ad hoc means and no systematic understanding was available at the time. It is only since the 1990 result of Feige, Goldwasser, LovĂĄsz, Safra and Szegedy on the inapproximability of
1469: 232:. In other words, although NP-complete problems may be equivalent (under polynomial-time reductions) to each other from the perspective of exact solutions, the corresponding optimization problems behave very differently from the perspective of approximate solutions. 304:
While approximation algorithms always provide an a priori worst case guarantee (be it additive or multiplicative), in some cases they also provide an a posteriori guarantee that is often much better. This is often the case for algorithms that work by solving a
2406: 1421:) by demonstrating that there exist instances where the algorithm performs at the approximation limit, indicating the tightness of the bound. In this case, it's enough to construct an input instance designed to force the algorithm into a worst-case scenario. 1883: 2193: 391:
In other cases, even if the initial results are of purely theoretical interest, over time, with an improved understanding, the algorithms may be refined to become more practical. One such example is the initial PTAS for
1742: 3930: 1378: 1246: 3084:∓ Ï” for arbitrary Ï” > 0 but that the ratio has not (or cannot) be shown for Ï” = 0. An example of this is the optimal inapproximability — inexistence of approximation — ratio of 7 / 8 + Ï” for satisfiable 3025: 1624:{\displaystyle {\begin{cases}\mathrm {OPT} \leq f(x)\leq \rho \mathrm {OPT} ,\qquad {\mbox{if }}\rho >1;\\\rho \mathrm {OPT} \leq f(x)\leq \mathrm {OPT} ,\qquad {\mbox{if }}\rho <1.\end{cases}}} 1975:
For minimization problems, the two different guarantees provide the same result and that for maximization problems, a relative performance guarantee of ρ is equivalent to a performance guarantee of
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relaxation to get a fractional solution. Then converting this fractional solution into a feasible solution by some appropriate rounding. The popular relaxations include the following.
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where the non-existence of efficient algorithms with certain approximation ratios is proved (conditioned on widely believed hypotheses such as the P ≠ NP conjecture) by means of
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to either vertex from the graph. As any vertex cover of the input graph must use a distinct vertex to cover each edge that was considered in the process (since it forms a
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Goemans, Michel X.; Williamson, David P. (November 1995). "Improved Approximation Algorithms for Maximum Cut and Satisfiability Problems Using Semidefinite Programming".
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An Ï”-term may appear when an approximation algorithm introduces a multiplicative error and a constant error while the minimum optimum of instances of size
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on the size of problem instances. These two types of ratios are used because there exist algorithms where the difference between these two is significant.
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algorithm, the guarantee of the latter can be much better (indeed when the value of the LP relaxation is far from the size of the optimal vertex cover).
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problems) with provable guarantees on the distance of the returned solution to the optimal one. Approximation algorithms naturally arise in the field of
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of the optimization problem on the given input. For example, there is a different approximation algorithm for minimum vertex cover that solves a
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For some approximation algorithms it is possible to prove certain properties about the approximation of th.e optimum result. For example, a
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Lenstra, Jan Karel; Shmoys, David B.; Tardos, Éva (1990-01-01). "Approximation algorithms for scheduling unrelated parallel machines".
116:, which find reasonably good solutions on some inputs, but provide no clear indication at the outset on when they may succeed or fail. 4740: 3147:
can be solved by brute force, thereby showing an approximation ratio — existence of approximation algorithms with a guarantee — of
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Embedding the problem in some metric and then solving the problem on the metric. This is also known as metric embedding.
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By now there are several established techniques to design approximation algorithms. These include the following ones.
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Arora, S. (October 1997). "Nearly linear time approximation schemes for Euclidean TSP and other geometric problems".
3289: 3253: 3231: 2401:{\displaystyle R_{A}^{\infty }=\inf\{r\geq 1\mid \exists n\in \mathbb {Z} ^{+},R_{A}(x)\leq r,\forall x,|x|\geq n\}.} 647: 3224: 4312: 4006: 342:, that modern tools for proving inapproximability results were uncovered. The PCP theorem, for example, shows that 4251: 3671:
Arora, S. (October 1996). "Polynomial time approximation schemes for Euclidean TSP and other geometric problems".
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Not all approximation algorithms are suitable for direct practical applications. Some involve solving non-trivial
149:), the vertex cover produced, therefore, is at most twice as large as the optimal one. In other words, this is a 17: 4589: 1084: 839: 355: 347: 335: 2900: 1380:, which in turn means the optimal solution divided by the solution taken by the algorithm achieves a ratio of 1248:, which in turn means the solution taken by the algorithm divided by the optimal solution achieves a ratio of 4697: 4317: 377: 310: 4633: 4601: 120: 105: 62: 3511:
Karpinski, Marek; Lampis, Michael; Schmied, Richard (2015-12-01). "New inapproximability bounds for TSP".
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Complexity and Approximation: Combinatorial Optimization Problems and their Approximability Properties
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or PTAS). Others are impossible to approximate within any constant, or even polynomial, factor unless
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conjecture. Under this conjecture, a wide class of optimization problems cannot be solved exactly in
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certifying the quality of the returned solutions in the worst case. This distinguishes them from
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Feige, Uriel; Goldwasser, Shafi; LovĂĄsz, Laszlo; Safra, Shmuel; Szegedy, Mario (March 1996).
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G. Ausiello; P. Crescenzi; G. Gambosi; V. Kann; A. Marchetti-Spaccamela; M. Protasi (1999).
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Random sampling and the use of randomness in general in conjunction with the methods above.
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approximation. Yet, within a year these ideas were incorporated into a near-linear time
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In the literature, an approximation ratio for a maximization (minimization) problem of
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Proceedings of the twenty-third annual ACM symposium on Theory of computing - STOC '91
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Approximation algorithms as a research area is closely related to and informed by
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is defined to be an algorithm for which it has been proven that the value/cost,
4519: 4404: 4291: 4225: 4196: 3905: 3872: 3534: 3496: 3479: 359: 225: 2188:{\displaystyle \mathrm {P} _{A}=\inf\{r\geq 1\mid R_{A}(x)\leq r,\forall x\}.} 4734: 4677: 4661: 3731: 3690: 3616: 3575: 3456: 3358: 3299: 397: 50: 3942:. Chapter 9: Various Notions of Approximations: Good, Better, Best, and More 86: 27:
Class of algorithms that find approximate solutions to optimization problems
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is the class of problems with some constant-factor approximation algorithm
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NP-hard problems vary greatly in their approximability; some, such as the
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guarantees to return solutions with a performance guarantee of at most
3388:. New Orleans, Louisiana, United States: ACM Press. pp. 134–144. 4028: 3279: 1459:
will not be more (or less, depending on the situation) than a factor
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Proceedings 38th Annual Symposium on Foundations of Computer Science
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considers guarantees in terms of the rank of the computed solution.
3085: 1737:{\displaystyle (\mathrm {OPT} -c)\leq f(x)\leq (\mathrm {OPT} +c).} 3525: 1373:{\displaystyle {\frac {c(s^{*}(i))}{c(A_{\Pi }(i))}}\leq \rho (n)} 1241:{\displaystyle {\frac {c(A_{\Pi }(i))}{c(s^{*}(i))}}\leq \rho (n)} 4424: 3922:. Chapter 35: Approximation Algorithms, pp. 1022–1056. 3673:
Proceedings of 37th Conference on Foundations of Computer Science
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all achieve the optimal approximation ratio, assuming P ≠ NP.
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A simple example of an approximation algorithm is one for the
3080:+ Ï”) means that the algorithm has an approximation ratio of 3799:
On the Approximability of NP-complete Optimization Problems
1617: 3547: 3131:. Given arbitrary Ï” > 0, one can choose a large enough 3020:{\displaystyle (1-c)^{-1}\mathrm {OPT} +c\mathrm {WORST} } 3480:"Vertex cover might be hard to approximate to within 2−Δ" 3182: 541: 3767: 3765: 3763: 3761: 3759: 642:
the set of solutions, we can define the cost function:
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Pierluigi Crescenzi, Viggo Kann, MagnĂșs HalldĂłrsson,
3640:"Approximation algorithms for combinatorial problems" 3034: 2957: 2903: 2859: 2827: 2795: 2762: 2724: 2710:{\displaystyle (1-c)\mathrm {OPT} +c\mathrm {WORST} } 2657: 2613: 2569: 2537: 2495: 2462: 2275: 2240: 2204: 2111: 2060: 2023: 1981: 1776: 1666: 1472: 1386: 1290: 1254: 1158: 1087: 1058: 1001: 965: 930: 842: 800: 771: 695: 650: 628: 608: 588: 554: 518: 480: 454: 410: 196: 170: 164:, can be approximated within a multiplicative factor 4541: 3756: 153:
with an approximation factor of 2. Under the recent
3914:, Second Edition. MIT Press and McGraw-Hill, 2001. 3809: 3326: 3054: 3019: 2942: 2888: 2844: 2812: 2780: 2744: 2709: 2642: 2598: 2554: 2522: 2480: 2400: 2258: 2219: 2187: 2082: 2038: 2003: 1877: 1736: 1623: 1401: 1372: 1269: 1240: 1136: 1073: 1036: 984: 951: 914: 828: 784: 755: 677: 634: 614: 594: 572: 530: 504: 466: 440: 208: 182: 3424: 3175:- a type of approximation algorithm that runs in 2227:is the largest bound on the approximation ratio, 100:of approximation algorithms crucially involves a 4732: 3945: 3379: 2294: 2127: 1798: 3380:Agrawal, Ajit; Klein, Philip; Ravi, R. (1991). 3273: 3271: 3111:does. In this case, the approximation ratio is 678:{\displaystyle c:S\rightarrow \mathbb {R} ^{+}} 3791: 3789: 3787: 3785: 3783: 3589:Arora, Sanjeev; Safra, Shmuel (January 1998). 2054:refers to an instance of a problem, and where 1463:times the value, OPT, of an optimum solution. 792:for a maximization or a minimization problem: 235: 4014: 3931:Approximation Algorithms for NP-Hard problems 384:relaxations (which may themselves invoke the 157:, this factor is even the best possible one. 4575: 3815: 3312:: CS1 maint: multiple names: authors list ( 3268: 2392: 2297: 2179: 2130: 317: 4053: 3780: 1653:, if it has been proven for every instance 4021: 4007: 3795: 3588: 2411:That is to say that it is the same as the 404:) which had a prohibitive running time of 299: 77:is the classic approximation algorithm of 4267: 3836: 3680: 3655: 3606: 3565: 3524: 3495: 3478:Khot, Subhash; Regev, Oded (2008-05-01). 3477: 3438: 3340: 3254:Learn how and when to remove this message 2323: 1952:)-approximation algorithm is said to be r 1424: 1137:{\displaystyle \forall i\in I\ s.t.|i|=n} 915:{\displaystyle c(s^{*})=min/max\ c(S(i))} 665: 4255:Optimization computes maxima and minima. 3992:A compendium of NP optimization problems 3871: 3821:"Some Optimal Inapproximability Results" 3277: 3217:This article includes a list of general 2943:{\displaystyle (1-c)^{-1}\mathrm {OPT} } 1908:is an optimal solution. If an algorithm 65:as a consequence of the widely believed 4339: 3644:Journal of Computer and System Sciences 3637: 3513:Journal of Computer and System Sciences 3484:Journal of Computer and System Sciences 3143:. For every fixed Ï”, instances of size 151:constant-factor approximation algorithm 14: 4733: 3955:The Design of Approximation Algorithms 3281:The design of approximation algorithms 4659: 4475: 4451:Principal pivoting algorithm of Lemke 4338: 4266: 4052: 4002: 3721: 3670: 3173:Parameterized approximation algorithm 1932:)-approximation algorithm and has an 542:Structure of approximation algorithms 3203: 3098:polynomial-time approximation scheme 2523:{\displaystyle r^{-1}\mathrm {OPT} } 1896:) is the value/cost of the solution 1642:. An approximation algorithm has an 1037:{\displaystyle A_{\Pi }(i)\in S_{i}} 218:polynomial-time approximation scheme 3096:= 1, the problem is said to have a 2889:{\displaystyle (1+c)\mathrm {OPT} } 2845:{\displaystyle \rho \mathrm {OPT} } 2643:{\displaystyle (1-c)\mathrm {OPT} } 2599:{\displaystyle (1-c)\mathrm {OPT} } 2555:{\displaystyle \rho \mathrm {OPT} } 687:and the set of feasible solutions: 24: 4660: 4250: 4095:Successive parabolic interpolation 3223:it lacks sufficient corresponding 3189:Approximation-preserving reduction 3042: 3039: 3036: 3013: 3010: 3007: 3004: 3001: 2990: 2987: 2984: 2936: 2933: 2930: 2882: 2879: 2876: 2838: 2835: 2832: 2806: 2803: 2800: 2732: 2729: 2726: 2703: 2700: 2697: 2694: 2691: 2680: 2677: 2674: 2636: 2633: 2630: 2592: 2589: 2586: 2548: 2545: 2542: 2516: 2513: 2510: 2364: 2312: 2286: 2251: 2207: 2173: 2114: 2026: 1964:or have an approximation ratio of 1718: 1715: 1712: 1677: 1674: 1671: 1590: 1587: 1584: 1561: 1558: 1555: 1520: 1517: 1514: 1488: 1485: 1482: 1335: 1173: 1088: 1007: 743: 696: 589: 555: 441:{\displaystyle n^{O(1/\epsilon )}} 346:1974 approximation algorithms for 25: 4757: 4476: 4415:Projective algorithm of Karmarkar 3975: 3486:. Computational Complexity 2003. 4410:Ellipsoid algorithm of Khachiyan 4313:Sequential quadratic programming 4150:Broyden–Fletcher–Goldfarb–Shanno 3934:, PWS Publishing Company, 1997. 3638:Johnson, David S. (1974-12-01). 3278:Bernard., Shmoys, David (2011). 3208: 3092:. As mentioned previously, when 3067: 3055:{\displaystyle \mathrm {OPT} +c} 2745:{\displaystyle \mathrm {OPT} -c} 2220:{\displaystyle \mathrm {P} _{A}} 2090:is the performance guarantee of 2046:of some approximation algorithm 2039:{\displaystyle \mathrm {P} _{A}} 1413:The approximation can be proven 119:There is widespread interest in 93:on unrelated parallel machines. 4741:Computational complexity theory 3715: 3664: 2813:{\displaystyle r\mathrm {OPT} } 2259:{\displaystyle R_{A}^{\infty }} 1944:). Likewise, a problem with an 1597: 1527: 1447:), of the approximate solution 546:Given an optimization problem: 365: 135: 4368:Reduced gradient (Frank–Wolfe) 3631: 3582: 3541: 3504: 3471: 3418: 3373: 3320: 3284:. Cambridge University Press. 2971: 2958: 2917: 2904: 2872: 2860: 2772: 2766: 2670: 2658: 2626: 2614: 2582: 2570: 2472: 2466: 2382: 2374: 2352: 2346: 2161: 2155: 2077: 2071: 2016:absolute performance guarantee 1850: 1844: 1829: 1823: 1792: 1780: 1728: 1708: 1702: 1696: 1687: 1667: 1644:absolute performance guarantee 1640:relative performance guarantee 1577: 1571: 1504: 1498: 1396: 1390: 1367: 1361: 1349: 1346: 1340: 1327: 1319: 1316: 1310: 1297: 1264: 1258: 1235: 1229: 1217: 1214: 1208: 1195: 1187: 1184: 1178: 1165: 1124: 1116: 1068: 1062: 1018: 1012: 946: 940: 909: 906: 900: 894: 859: 846: 823: 817: 720: 714: 660: 573:{\displaystyle \Pi :I\times S} 531:{\displaystyle \epsilon >0} 499: 484: 433: 419: 258:(which is also often used for 209:{\displaystyle \epsilon >0} 13: 1: 4698:Spiral optimization algorithm 4318:Successive linear programming 3865: 3657:10.1016/S0022-0000(74)80044-9 2098:(i.e. ρ for problem instance 829:{\displaystyle s^{*}\in S(i)} 602:is an approximation problem, 311:linear programming relaxation 4436:Simplex algorithm of Dantzig 4308:Augmented Lagrangian methods 3199: 2233:asymptotic performance ratio 2004:{\displaystyle r=\rho ^{-1}} 260:parameterized approximations 126:Goemans–Williamson algorithm 121:theoretical computer science 63:theoretical computer science 7: 3154: 985:{\displaystyle s\neq s^{*}} 512:algorithm for any constant 467:{\displaystyle 1+\epsilon } 236:Algorithm design techniques 183:{\displaystyle 1+\epsilon } 10: 4762: 3959:Cambridge University Press 3911:Introduction to Algorithms 3535:10.1016/j.jcss.2015.06.003 3497:10.1016/j.jcss.2007.06.019 3123:∓ o(1) for some constants 2413:absolute performance ratio 924:Given a feasible solution 765:finding the best solution 505:{\displaystyle O(n\log n)} 369: 4715: 4668: 4655: 4639:Push–relabel maximum flow 4614: 4530: 4488: 4484: 4471: 4441:Revised simplex algorithm 4423: 4395: 4381: 4351: 4347: 4334: 4300: 4279: 4275: 4262: 4248: 4224: 4172: 4135: 4112: 4103: 4065: 4061: 4048: 2781:{\displaystyle f(x)\leq } 2481:{\displaystyle f(x)\geq } 952:{\displaystyle s\in S(i)} 318:Hardness of approximation 230:theory of NP-completeness 4746:Approximation algorithms 4164:Symmetric rank-one (SR1) 4145:Berndt–Hall–Hall–Hausman 3877:Approximation Algorithms 3732:10.1109/SFCS.1997.646145 3691:10.1109/SFCS.1996.548458 3329:Mathematical Programming 3151:∓ Ï” for every Ï” > 0. 2083:{\displaystyle R_{A}(x)} 1434:-approximation algorithm 1402:{\displaystyle \rho (n)} 1270:{\displaystyle \rho (n)} 1074:{\displaystyle \rho (n)} 324:inapproximability theory 279:Semidefinite programming 224:, as in the case of the 40:approximation algorithms 4688:Parallel metaheuristics 4496:Approximation algorithm 4207:Powell's dog leg method 4159:Davidon–Fletcher–Powell 4055:Unconstrained nonlinear 3238:more precise citations. 3139:/ OPT < Ï” for every 2423:Performance guarantees 1044:, the algorithm has an 300:A posteriori guarantees 155:unique games conjecture 4673:Evolutionary algorithm 4256: 3056: 3021: 2944: 2890: 2846: 2814: 2782: 2746: 2711: 2644: 2600: 2556: 2524: 2482: 2402: 2260: 2221: 2189: 2084: 2040: 2005: 1879: 1738: 1625: 1425:Performance guarantees 1403: 1374: 1271: 1242: 1138: 1075: 1038: 986: 953: 916: 830: 786: 757: 679: 636: 622:the set of inputs and 616: 596: 574: 532: 506: 468: 442: 400:(and independently by 226:maximum clique problem 210: 184: 4446:Criss-cross algorithm 4269:Constrained nonlinear 4254: 4075:Golden-section search 3847:10.1145/502090.502098 3608:10.1145/273865.273901 3567:10.1145/226643.226652 3449:10.1145/227683.227684 3394:10.1145/103418.103437 3057: 3022: 2945: 2891: 2847: 2815: 2783: 2747: 2712: 2645: 2601: 2557: 2525: 2483: 2415:, with a lower bound 2403: 2261: 2222: 2190: 2085: 2041: 2006: 1880: 1749:performance guarantee 1739: 1626: 1404: 1375: 1272: 1243: 1139: 1076: 1039: 995:Specifically, having 987: 954: 917: 831: 787: 785:{\displaystyle s^{*}} 758: 680: 637: 617: 597: 575: 533: 507: 469: 443: 211: 185: 55:optimization problems 4363:Cutting-plane method 3947:Williamson, David P. 3898:Charles E. Leiserson 3879:. Berlin: Springer. 3726:. pp. 554–563. 3382:"When trees collide" 3107:goes to infinity as 3032: 2955: 2901: 2857: 2825: 2793: 2760: 2722: 2655: 2611: 2567: 2535: 2493: 2460: 2273: 2238: 2202: 2198:That is to say that 2109: 2058: 2021: 1979: 1774: 1664: 1470: 1384: 1288: 1252: 1156: 1085: 1056: 1046:approximation factor 999: 963: 928: 840: 798: 769: 693: 648: 626: 606: 595:{\displaystyle \Pi } 586: 552: 516: 478: 452: 408: 194: 168: 142:minimum vertex cover 4693:Simulated annealing 4511:Integer programming 4501:Dynamic programming 4341:Convex optimization 4202:Levenberg–Marquardt 3796:Viggo Kann (1992). 3161:Domination analysis 3135:such that the term 2424: 2290: 2255: 1934:approximation ratio 1419:tight approximation 1050:approximation ratio 386:ellipsoid algorithm 286:Primal-dual methods 256:dynamic programming 36:operations research 4373:Subgradient method 4257: 4182:Conjugate gradient 4090:Nelder–Mead method 3953:(April 26, 2011), 3873:Vazirani, Vijay V. 3825:Journal of the ACM 3351:10.1007/BF01585745 3052: 3017: 2940: 2886: 2842: 2810: 2778: 2742: 2707: 2640: 2596: 2552: 2520: 2478: 2422: 2398: 2276: 2256: 2241: 2217: 2185: 2080: 2036: 2001: 1875: 1734: 1621: 1616: 1603: 1533: 1399: 1370: 1267: 1238: 1134: 1071: 1034: 982: 949: 912: 826: 782: 753: 675: 632: 612: 592: 570: 528: 502: 464: 438: 378:linear programming 372:Galactic algorithm 273:Linear programming 267:convex programming 206: 180: 114:genetic algorithms 102:mathematical proof 4728: 4727: 4711: 4710: 4651: 4650: 4647: 4646: 4610: 4609: 4571: 4570: 4467: 4466: 4463: 4462: 4459: 4458: 4330: 4329: 4326: 4325: 4246: 4245: 4242: 4241: 4220: 4219: 3987:Gerhard Woeginger 3926:Dorit S. Hochbaum 3886:978-3-540-65367-7 3741:978-0-8186-8197-4 3700:978-0-8186-7594-2 3675:. pp. 2–11. 3403:978-0-89791-397-3 3264: 3263: 3256: 3088:instances due to 3065: 3064: 1924:is said to be an 1900:for the instance 1865: 1833: 1759:), of a solution 1602: 1532: 1455:) to an instance 1353: 1221: 1102: 890: 635:{\displaystyle S} 615:{\displaystyle I} 307:convex relaxation 16:(Redirected from 4753: 4657: 4656: 4573: 4572: 4539: 4538: 4516:Branch and bound 4506:Greedy algorithm 4486: 4485: 4473: 4472: 4393: 4392: 4349: 4348: 4336: 4335: 4277: 4276: 4264: 4263: 4212:Truncated Newton 4127:Wolfe conditions 4110: 4109: 4063: 4062: 4050: 4049: 4023: 4016: 4009: 4000: 3999: 3971: 3951:Shmoys, David B. 3902:Ronald L. Rivest 3894:Thomas H. Cormen 3890: 3859: 3858: 3840: 3813: 3807: 3806: 3804: 3793: 3778: 3777: 3769: 3754: 3753: 3719: 3713: 3712: 3684: 3668: 3662: 3661: 3659: 3635: 3629: 3628: 3610: 3586: 3580: 3579: 3569: 3545: 3539: 3538: 3528: 3519:(8): 1665–1677. 3508: 3502: 3501: 3499: 3475: 3469: 3468: 3442: 3433:(6): 1115–1145. 3422: 3416: 3415: 3377: 3371: 3370: 3344: 3335:(1–3): 259–271. 3324: 3318: 3317: 3311: 3303: 3275: 3259: 3252: 3248: 3245: 3239: 3234:this article by 3225:inline citations 3212: 3211: 3204: 3061: 3059: 3058: 3053: 3045: 3026: 3024: 3023: 3018: 3016: 2993: 2982: 2981: 2949: 2947: 2946: 2941: 2939: 2928: 2927: 2895: 2893: 2892: 2887: 2885: 2851: 2849: 2848: 2843: 2841: 2819: 2817: 2816: 2811: 2809: 2787: 2785: 2784: 2779: 2751: 2749: 2748: 2743: 2735: 2716: 2714: 2713: 2708: 2706: 2683: 2649: 2647: 2646: 2641: 2639: 2605: 2603: 2602: 2597: 2595: 2561: 2559: 2558: 2553: 2551: 2529: 2527: 2526: 2521: 2519: 2508: 2507: 2487: 2485: 2484: 2479: 2448:norm. rel. error 2425: 2421: 2407: 2405: 2404: 2399: 2385: 2377: 2345: 2344: 2332: 2331: 2326: 2289: 2284: 2265: 2263: 2262: 2257: 2254: 2249: 2226: 2224: 2223: 2218: 2216: 2215: 2210: 2194: 2192: 2191: 2186: 2154: 2153: 2123: 2122: 2117: 2089: 2087: 2086: 2081: 2070: 2069: 2045: 2043: 2042: 2037: 2035: 2034: 2029: 2010: 2008: 2007: 2002: 2000: 1999: 1884: 1882: 1881: 1876: 1871: 1867: 1866: 1864: 1853: 1839: 1834: 1832: 1818: 1807: 1743: 1741: 1740: 1735: 1721: 1680: 1630: 1628: 1627: 1622: 1620: 1619: 1604: 1600: 1593: 1564: 1534: 1530: 1523: 1491: 1408: 1406: 1405: 1400: 1379: 1377: 1376: 1371: 1354: 1352: 1339: 1338: 1322: 1309: 1308: 1292: 1276: 1274: 1273: 1268: 1247: 1245: 1244: 1239: 1222: 1220: 1207: 1206: 1190: 1177: 1176: 1160: 1143: 1141: 1140: 1135: 1127: 1119: 1100: 1080: 1078: 1077: 1072: 1043: 1041: 1040: 1035: 1033: 1032: 1011: 1010: 991: 989: 988: 983: 981: 980: 958: 956: 955: 950: 921: 919: 918: 913: 888: 878: 858: 857: 835: 833: 832: 827: 810: 809: 791: 789: 788: 783: 781: 780: 762: 760: 759: 754: 752: 751: 750: 684: 682: 681: 676: 674: 673: 668: 641: 639: 638: 633: 621: 619: 618: 613: 601: 599: 598: 593: 579: 577: 576: 571: 537: 535: 534: 529: 511: 509: 508: 503: 473: 471: 470: 465: 447: 445: 444: 439: 437: 436: 429: 254:Enumeration and 245:Greedy algorithm 215: 213: 212: 207: 190:, for any fixed 189: 187: 186: 181: 162:knapsack problem 32:computer science 21: 4761: 4760: 4756: 4755: 4754: 4752: 4751: 4750: 4731: 4730: 4729: 4724: 4707: 4664: 4643: 4606: 4567: 4544: 4533: 4526: 4480: 4455: 4419: 4386: 4377: 4354: 4343: 4322: 4296: 4292:Penalty methods 4287:Barrier methods 4271: 4258: 4238: 4234:Newton's method 4216: 4168: 4131: 4099: 4080:Powell's method 4057: 4044: 4027: 3983:Marek Karpinski 3978: 3969: 3887: 3868: 3863: 3862: 3838:10.1.1.638.2808 3814: 3810: 3802: 3794: 3781: 3770: 3757: 3742: 3720: 3716: 3701: 3669: 3665: 3636: 3632: 3587: 3583: 3546: 3542: 3509: 3505: 3476: 3472: 3423: 3419: 3404: 3378: 3374: 3325: 3321: 3305: 3304: 3292: 3276: 3269: 3260: 3249: 3243: 3240: 3230:Please help to 3229: 3213: 3209: 3202: 3194:Exact algorithm 3157: 3070: 3035: 3033: 3030: 3029: 3000: 2983: 2974: 2970: 2956: 2953: 2952: 2929: 2920: 2916: 2902: 2899: 2898: 2875: 2858: 2855: 2854: 2831: 2826: 2823: 2822: 2799: 2794: 2791: 2790: 2761: 2758: 2757: 2725: 2723: 2720: 2719: 2690: 2673: 2656: 2653: 2652: 2629: 2612: 2609: 2608: 2585: 2568: 2565: 2564: 2541: 2536: 2533: 2532: 2509: 2500: 2496: 2494: 2491: 2490: 2461: 2458: 2457: 2381: 2373: 2340: 2336: 2327: 2322: 2321: 2285: 2280: 2274: 2271: 2270: 2250: 2245: 2239: 2236: 2235: 2211: 2206: 2205: 2203: 2200: 2199: 2149: 2145: 2118: 2113: 2112: 2110: 2107: 2106: 2065: 2061: 2059: 2056: 2055: 2030: 2025: 2024: 2022: 2019: 2018: 1992: 1988: 1980: 1977: 1976: 1854: 1840: 1838: 1819: 1808: 1806: 1805: 1801: 1775: 1772: 1771: 1763:to an instance 1747:Similarly, the 1711: 1670: 1665: 1662: 1661: 1615: 1614: 1598: 1583: 1554: 1548: 1547: 1528: 1513: 1481: 1474: 1473: 1471: 1468: 1467: 1427: 1385: 1382: 1381: 1334: 1330: 1323: 1304: 1300: 1293: 1291: 1289: 1286: 1285: 1253: 1250: 1249: 1202: 1198: 1191: 1172: 1168: 1161: 1159: 1157: 1154: 1153: 1123: 1115: 1086: 1083: 1082: 1057: 1054: 1053: 1028: 1024: 1006: 1002: 1000: 997: 996: 976: 972: 964: 961: 960: 929: 926: 925: 874: 853: 849: 841: 838: 837: 805: 801: 799: 796: 795: 776: 772: 770: 767: 766: 746: 742: 726: 694: 691: 690: 669: 664: 663: 649: 646: 645: 627: 624: 623: 607: 604: 603: 587: 584: 583: 553: 550: 549: 544: 517: 514: 513: 479: 476: 475: 453: 450: 449: 425: 415: 411: 409: 406: 405: 402:Joseph Mitchell 374: 368: 356:independent set 338:and the famous 336:Independent Set 320: 302: 238: 195: 192: 191: 169: 166: 165: 138: 96:The design and 71:polynomial time 57:(in particular 28: 23: 22: 18:Approximability 15: 12: 11: 5: 4759: 4749: 4748: 4743: 4726: 4725: 4723: 4722: 4716: 4713: 4712: 4709: 4708: 4706: 4705: 4700: 4695: 4690: 4685: 4680: 4675: 4669: 4666: 4665: 4662:Metaheuristics 4653: 4652: 4649: 4648: 4645: 4644: 4642: 4641: 4636: 4634:Ford–Fulkerson 4631: 4626: 4620: 4618: 4612: 4611: 4608: 4607: 4605: 4604: 4602:Floyd–Warshall 4599: 4594: 4593: 4592: 4581: 4579: 4569: 4568: 4566: 4565: 4560: 4555: 4549: 4547: 4536: 4528: 4527: 4525: 4524: 4523: 4522: 4508: 4503: 4498: 4492: 4490: 4482: 4481: 4469: 4468: 4465: 4464: 4461: 4460: 4457: 4456: 4454: 4453: 4448: 4443: 4438: 4432: 4430: 4421: 4420: 4418: 4417: 4412: 4407: 4405:Affine scaling 4401: 4399: 4397:Interior point 4390: 4379: 4378: 4376: 4375: 4370: 4365: 4359: 4357: 4345: 4344: 4332: 4331: 4328: 4327: 4324: 4323: 4321: 4320: 4315: 4310: 4304: 4302: 4301:Differentiable 4298: 4297: 4295: 4294: 4289: 4283: 4281: 4273: 4272: 4260: 4259: 4249: 4247: 4244: 4243: 4240: 4239: 4237: 4236: 4230: 4228: 4222: 4221: 4218: 4217: 4215: 4214: 4209: 4204: 4199: 4194: 4189: 4184: 4178: 4176: 4170: 4169: 4167: 4166: 4161: 4156: 4147: 4141: 4139: 4133: 4132: 4130: 4129: 4124: 4118: 4116: 4107: 4101: 4100: 4098: 4097: 4092: 4087: 4082: 4077: 4071: 4069: 4059: 4058: 4046: 4045: 4026: 4025: 4018: 4011: 4003: 3997: 3996: 3977: 3976:External links 3974: 3973: 3972: 3968:978-0521195270 3967: 3943: 3923: 3906:Clifford Stein 3891: 3885: 3867: 3864: 3861: 3860: 3831:(4): 798–859. 3808: 3779: 3755: 3740: 3714: 3699: 3682:10.1.1.32.3376 3663: 3650:(3): 256–278. 3630: 3581: 3560:(2): 268–292. 3540: 3503: 3490:(3): 335–349. 3470: 3440:10.1.1.34.8500 3417: 3402: 3372: 3342:10.1.1.115.708 3319: 3290: 3266: 3265: 3262: 3261: 3216: 3214: 3207: 3201: 3198: 3197: 3196: 3191: 3186: 3180: 3170: 3164: 3156: 3153: 3069: 3066: 3063: 3062: 3051: 3048: 3044: 3041: 3038: 3027: 3015: 3012: 3009: 3006: 3003: 2999: 2996: 2992: 2989: 2986: 2980: 2977: 2973: 2969: 2966: 2963: 2960: 2950: 2938: 2935: 2932: 2926: 2923: 2919: 2915: 2912: 2909: 2906: 2896: 2884: 2881: 2878: 2874: 2871: 2868: 2865: 2862: 2852: 2840: 2837: 2834: 2830: 2820: 2808: 2805: 2802: 2798: 2788: 2777: 2774: 2771: 2768: 2765: 2753: 2752: 2741: 2738: 2734: 2731: 2728: 2717: 2705: 2702: 2699: 2696: 2693: 2689: 2686: 2682: 2679: 2676: 2672: 2669: 2666: 2663: 2660: 2650: 2638: 2635: 2632: 2628: 2625: 2622: 2619: 2616: 2606: 2594: 2591: 2588: 2584: 2581: 2578: 2575: 2572: 2562: 2550: 2547: 2544: 2540: 2530: 2518: 2515: 2512: 2506: 2503: 2499: 2488: 2477: 2474: 2471: 2468: 2465: 2453: 2452: 2449: 2446: 2443: 2440: 2434: 2428: 2409: 2408: 2397: 2394: 2391: 2388: 2384: 2380: 2376: 2372: 2369: 2366: 2363: 2360: 2357: 2354: 2351: 2348: 2343: 2339: 2335: 2330: 2325: 2320: 2317: 2314: 2311: 2308: 2305: 2302: 2299: 2296: 2293: 2288: 2283: 2279: 2253: 2248: 2244: 2214: 2209: 2196: 2195: 2184: 2181: 2178: 2175: 2172: 2169: 2166: 2163: 2160: 2157: 2152: 2148: 2144: 2141: 2138: 2135: 2132: 2129: 2126: 2121: 2116: 2079: 2076: 2073: 2068: 2064: 2033: 2028: 1998: 1995: 1991: 1987: 1984: 1886: 1885: 1874: 1870: 1863: 1860: 1857: 1852: 1849: 1846: 1843: 1837: 1831: 1828: 1825: 1822: 1817: 1814: 1811: 1804: 1800: 1797: 1794: 1791: 1788: 1785: 1782: 1779: 1767:is defined as 1745: 1744: 1733: 1730: 1727: 1724: 1720: 1717: 1714: 1710: 1707: 1704: 1701: 1698: 1695: 1692: 1689: 1686: 1683: 1679: 1676: 1673: 1669: 1638:is called the 1632: 1631: 1618: 1613: 1610: 1607: 1596: 1592: 1589: 1586: 1582: 1579: 1576: 1573: 1570: 1567: 1563: 1560: 1557: 1553: 1550: 1549: 1546: 1543: 1540: 1537: 1526: 1522: 1519: 1516: 1512: 1509: 1506: 1503: 1500: 1497: 1494: 1490: 1487: 1484: 1480: 1479: 1477: 1426: 1423: 1411: 1410: 1398: 1395: 1392: 1389: 1369: 1366: 1363: 1360: 1357: 1351: 1348: 1345: 1342: 1337: 1333: 1329: 1326: 1321: 1318: 1315: 1312: 1307: 1303: 1299: 1296: 1278: 1266: 1263: 1260: 1257: 1237: 1234: 1231: 1228: 1225: 1219: 1216: 1213: 1210: 1205: 1201: 1197: 1194: 1189: 1186: 1183: 1180: 1175: 1171: 1167: 1164: 1133: 1130: 1126: 1122: 1118: 1114: 1111: 1108: 1105: 1099: 1096: 1093: 1090: 1070: 1067: 1064: 1061: 1031: 1027: 1023: 1020: 1017: 1014: 1009: 1005: 979: 975: 971: 968: 948: 945: 942: 939: 936: 933: 911: 908: 905: 902: 899: 896: 893: 887: 884: 881: 877: 873: 870: 867: 864: 861: 856: 852: 848: 845: 825: 822: 819: 816: 813: 808: 804: 779: 775: 749: 745: 741: 738: 735: 732: 729: 725: 722: 719: 716: 713: 710: 707: 704: 701: 698: 672: 667: 662: 659: 656: 653: 631: 611: 591: 569: 566: 563: 560: 557: 543: 540: 527: 524: 521: 501: 498: 495: 492: 489: 486: 483: 463: 460: 457: 435: 432: 428: 424: 421: 418: 414: 367: 364: 319: 316: 301: 298: 297: 296: 293: 290: 287: 284: 283: 282: 276: 263: 252: 247: 237: 234: 205: 202: 199: 179: 176: 173: 137: 134: 26: 9: 6: 4: 3: 2: 4758: 4747: 4744: 4742: 4739: 4738: 4736: 4721: 4718: 4717: 4714: 4704: 4701: 4699: 4696: 4694: 4691: 4689: 4686: 4684: 4681: 4679: 4678:Hill climbing 4676: 4674: 4671: 4670: 4667: 4663: 4658: 4654: 4640: 4637: 4635: 4632: 4630: 4627: 4625: 4622: 4621: 4619: 4617: 4616:Network flows 4613: 4603: 4600: 4598: 4595: 4591: 4588: 4587: 4586: 4583: 4582: 4580: 4578: 4577:Shortest path 4574: 4564: 4561: 4559: 4556: 4554: 4551: 4550: 4548: 4546: 4545:spanning tree 4540: 4537: 4535: 4529: 4521: 4517: 4514: 4513: 4512: 4509: 4507: 4504: 4502: 4499: 4497: 4494: 4493: 4491: 4487: 4483: 4479: 4478:Combinatorial 4474: 4470: 4452: 4449: 4447: 4444: 4442: 4439: 4437: 4434: 4433: 4431: 4429: 4426: 4422: 4416: 4413: 4411: 4408: 4406: 4403: 4402: 4400: 4398: 4394: 4391: 4389: 4384: 4380: 4374: 4371: 4369: 4366: 4364: 4361: 4360: 4358: 4356: 4350: 4346: 4342: 4337: 4333: 4319: 4316: 4314: 4311: 4309: 4306: 4305: 4303: 4299: 4293: 4290: 4288: 4285: 4284: 4282: 4278: 4274: 4270: 4265: 4261: 4253: 4235: 4232: 4231: 4229: 4227: 4223: 4213: 4210: 4208: 4205: 4203: 4200: 4198: 4195: 4193: 4190: 4188: 4185: 4183: 4180: 4179: 4177: 4175: 4174:Other methods 4171: 4165: 4162: 4160: 4157: 4155: 4151: 4148: 4146: 4143: 4142: 4140: 4138: 4134: 4128: 4125: 4123: 4120: 4119: 4117: 4115: 4111: 4108: 4106: 4102: 4096: 4093: 4091: 4088: 4086: 4083: 4081: 4078: 4076: 4073: 4072: 4070: 4068: 4064: 4060: 4056: 4051: 4047: 4043: 4039: 4035: 4031: 4024: 4019: 4017: 4012: 4010: 4005: 4004: 4001: 3994: 3993: 3988: 3984: 3980: 3979: 3970: 3964: 3960: 3956: 3952: 3948: 3944: 3941: 3940:0-534-94968-1 3937: 3933: 3932: 3927: 3924: 3921: 3920:0-262-03293-7 3917: 3913: 3912: 3907: 3903: 3899: 3895: 3892: 3888: 3882: 3878: 3874: 3870: 3869: 3856: 3852: 3848: 3844: 3839: 3834: 3830: 3826: 3822: 3818: 3812: 3801: 3800: 3792: 3790: 3788: 3786: 3784: 3775: 3768: 3766: 3764: 3762: 3760: 3751: 3747: 3743: 3737: 3733: 3729: 3725: 3718: 3710: 3706: 3702: 3696: 3692: 3688: 3683: 3678: 3674: 3667: 3658: 3653: 3649: 3645: 3641: 3634: 3626: 3622: 3618: 3614: 3609: 3604: 3601:(1): 70–122. 3600: 3596: 3592: 3585: 3577: 3573: 3568: 3563: 3559: 3555: 3551: 3544: 3536: 3532: 3527: 3522: 3518: 3514: 3507: 3498: 3493: 3489: 3485: 3481: 3474: 3466: 3462: 3458: 3454: 3450: 3446: 3441: 3436: 3432: 3428: 3421: 3413: 3409: 3405: 3399: 3395: 3391: 3387: 3383: 3376: 3368: 3364: 3360: 3356: 3352: 3348: 3343: 3338: 3334: 3330: 3323: 3315: 3309: 3301: 3297: 3293: 3291:9780521195270 3287: 3283: 3282: 3274: 3272: 3267: 3258: 3255: 3247: 3237: 3233: 3227: 3226: 3220: 3215: 3206: 3205: 3195: 3192: 3190: 3187: 3184: 3181: 3178: 3174: 3171: 3168: 3165: 3162: 3159: 3158: 3152: 3150: 3146: 3142: 3138: 3134: 3130: 3126: 3122: 3118: 3114: 3110: 3106: 3101: 3099: 3095: 3091: 3087: 3083: 3079: 3075: 3068:Epsilon terms 3049: 3046: 3028: 2997: 2994: 2978: 2975: 2967: 2964: 2961: 2951: 2924: 2921: 2913: 2910: 2907: 2897: 2869: 2866: 2863: 2853: 2828: 2821: 2796: 2789: 2775: 2769: 2763: 2755: 2754: 2739: 2736: 2718: 2687: 2684: 2667: 2664: 2661: 2651: 2623: 2620: 2617: 2607: 2579: 2576: 2573: 2563: 2538: 2531: 2504: 2501: 2497: 2489: 2475: 2469: 2463: 2455: 2454: 2450: 2447: 2444: 2441: 2438: 2435: 2432: 2429: 2427: 2426: 2420: 2418: 2414: 2395: 2389: 2386: 2378: 2370: 2367: 2361: 2358: 2355: 2349: 2341: 2337: 2333: 2328: 2318: 2315: 2309: 2306: 2303: 2300: 2291: 2281: 2277: 2269: 2268: 2267: 2246: 2242: 2234: 2230: 2212: 2182: 2176: 2170: 2167: 2164: 2158: 2150: 2146: 2142: 2139: 2136: 2133: 2124: 2119: 2105: 2104: 2103: 2101: 2097: 2093: 2074: 2066: 2062: 2053: 2049: 2031: 2017: 2012: 1996: 1993: 1989: 1985: 1982: 1973: 1971: 1967: 1963: 1959: 1955: 1951: 1947: 1943: 1939: 1935: 1931: 1927: 1923: 1919: 1915: 1911: 1907: 1903: 1899: 1895: 1891: 1872: 1868: 1861: 1858: 1855: 1847: 1841: 1835: 1826: 1820: 1815: 1812: 1809: 1802: 1795: 1789: 1786: 1783: 1777: 1770: 1769: 1768: 1766: 1762: 1758: 1754: 1750: 1731: 1725: 1722: 1705: 1699: 1693: 1690: 1684: 1681: 1660: 1659: 1658: 1656: 1652: 1649: 1648:bounded error 1645: 1641: 1637: 1611: 1608: 1605: 1594: 1580: 1574: 1568: 1565: 1551: 1544: 1541: 1538: 1535: 1524: 1510: 1507: 1501: 1495: 1492: 1475: 1466: 1465: 1464: 1462: 1458: 1454: 1450: 1446: 1442: 1438: 1435: 1433: 1422: 1420: 1416: 1393: 1387: 1364: 1358: 1355: 1343: 1331: 1324: 1313: 1305: 1301: 1294: 1283: 1279: 1261: 1255: 1232: 1226: 1223: 1211: 1203: 1199: 1192: 1181: 1169: 1162: 1151: 1147: 1146: 1145: 1131: 1128: 1120: 1112: 1109: 1106: 1103: 1097: 1094: 1091: 1065: 1059: 1051: 1047: 1029: 1025: 1021: 1015: 1003: 993: 977: 973: 969: 966: 943: 937: 934: 931: 922: 903: 897: 891: 885: 882: 879: 875: 871: 868: 865: 862: 854: 850: 843: 820: 814: 811: 806: 802: 793: 777: 773: 763: 747: 739: 736: 733: 730: 727: 723: 717: 711: 708: 705: 702: 699: 688: 685: 670: 657: 654: 651: 643: 629: 609: 580: 567: 564: 561: 558: 547: 539: 525: 522: 519: 496: 493: 490: 487: 481: 461: 458: 455: 430: 426: 422: 416: 412: 403: 399: 398:Sanjeev Arora 395: 394:Euclidean TSP 389: 387: 383: 379: 373: 363: 361: 357: 353: 349: 345: 341: 337: 331: 329: 325: 315: 312: 308: 294: 291: 288: 285: 280: 277: 274: 271: 270: 268: 264: 261: 257: 253: 251: 248: 246: 243: 242: 241: 233: 231: 227: 223: 219: 203: 200: 197: 177: 174: 171: 163: 158: 156: 152: 148: 143: 133: 131: 127: 122: 117: 115: 111: 107: 103: 99: 94: 92: 88: 84: 80: 76: 72: 68: 64: 60: 56: 53:solutions to 52: 48: 45: 41: 37: 33: 19: 4683:Local search 4629:Edmonds–Karp 4585:Bellman–Ford 4495: 4355:minimization 4187:Gauss–Newton 4137:Quasi–Newton 4122:Trust region 4030:Optimization 3991: 3954: 3929: 3909: 3876: 3828: 3824: 3817:Johan HĂ„stad 3811: 3798: 3773: 3723: 3717: 3672: 3666: 3647: 3643: 3633: 3598: 3594: 3584: 3557: 3553: 3543: 3516: 3512: 3506: 3487: 3483: 3473: 3430: 3426: 3420: 3385: 3375: 3332: 3328: 3322: 3280: 3250: 3241: 3222: 3148: 3144: 3140: 3136: 3132: 3128: 3124: 3120: 3116: 3112: 3108: 3104: 3102: 3093: 3090:Johan HĂ„stad 3081: 3077: 3073: 3071: 2436: 2430: 2416: 2412: 2410: 2232: 2228: 2197: 2099: 2095: 2091: 2051: 2047: 2015: 2013: 1974: 1969: 1965: 1962:approximable 1961: 1957: 1953: 1949: 1945: 1941: 1937: 1933: 1929: 1925: 1921: 1917: 1913: 1909: 1905: 1901: 1897: 1893: 1889: 1887: 1764: 1760: 1756: 1752: 1748: 1746: 1654: 1650: 1647: 1643: 1639: 1635: 1633: 1460: 1456: 1452: 1448: 1444: 1440: 1436: 1431: 1430: 1428: 1418: 1414: 1412: 1282:maximization 1281: 1150:minimization 1149: 1049: 1045: 994: 923: 794: 764: 689: 686: 644: 581: 548: 545: 390: 382:semidefinite 375: 366:Practicality 332: 321: 303: 289:Dual fitting 250:Local search 239: 159: 139: 136:Introduction 118: 95: 74: 39: 29: 4703:Tabu search 4114:Convergence 4085:Line search 3236:introducing 2451:abs. error 1634:The factor 1144:, we have: 340:PCP theorem 281:relaxations 275:relaxations 130:maximum cut 51:approximate 4735:Categories 4534:algorithms 4042:heuristics 4034:Algorithms 3866:References 3244:April 2009 3219:references 3076:- Ï” (min: 2445:rel. error 2442:rel. error 370:See also: 328:reductions 265:Solving a 106:heuristics 91:scheduling 49:that find 47:algorithms 4489:Paradigms 4388:quadratic 4105:Gradients 4067:Functions 3833:CiteSeerX 3677:CiteSeerX 3617:0004-5411 3576:0004-5411 3526:1303.6437 3457:0004-5411 3435:CiteSeerX 3367:206799898 3359:0025-5610 3337:CiteSeerX 3308:cite book 3300:671709856 3200:Citations 2976:− 2965:− 2922:− 2911:− 2829:ρ 2776:≤ 2737:− 2665:− 2621:− 2577:− 2539:ρ 2502:− 2476:≥ 2387:≥ 2365:∀ 2356:≤ 2319:∈ 2313:∃ 2310:∣ 2304:≥ 2287:∞ 2252:∞ 2174:∀ 2165:≤ 2143:∣ 2137:≥ 1994:− 1990:ρ 1706:≤ 1691:≤ 1682:− 1606:ρ 1581:≤ 1566:≤ 1552:ρ 1536:ρ 1511:ρ 1508:≤ 1493:≤ 1388:ρ 1359:ρ 1356:≤ 1336:Π 1306:∗ 1284:problem: 1256:ρ 1227:ρ 1224:≤ 1204:∗ 1174:Π 1152:problem: 1095:∈ 1089:∀ 1060:ρ 1022:∈ 1008:Π 978:∗ 970:≠ 935:∈ 855:∗ 812:∈ 807:∗ 778:∗ 744:Π 731:∈ 703:∈ 697:∀ 661:→ 590:Π 565:× 556:Π 520:ϵ 494:⁡ 462:ϵ 431:ϵ 352:set cover 344:Johnson's 198:ϵ 178:ϵ 110:annealing 44:efficient 4720:Software 4597:Dijkstra 4428:exchange 4226:Hessians 4192:Gradient 3875:(2003). 3819:(1999). 3750:10656723 3465:15794408 3155:See also 3145:n < N 3119:/ OPT = 3086:MAX-3SAT 2050:, where 1920:), then 1601:if  1531:if  360:coloring 147:matching 108:such as 98:analysis 4563:Kruskal 4553:BorĆŻvka 4543:Minimum 4280:General 4038:methods 3855:5120748 3709:1499391 3412:1245448 3232:improve 2439:-approx 2433:-approx 959:, with 348:Max SAT 79:Lenstra 59:NP-hard 4425:Basis- 4383:Linear 4353:Convex 4197:Mirror 4154:L-BFGS 4040:, and 3965:  3938:  3928:, ed. 3918:  3904:, and 3883:  3853:  3835:  3748:  3738:  3707:  3697:  3679:  3625:751563 3623:  3615:  3595:J. ACM 3574:  3554:J. ACM 3463:  3455:  3437:  3427:J. ACM 3410:  3400:  3365:  3357:  3339:  3298:  3288:  3221:, but 2102:) is: 1888:where 1280:for a 1148:for a 1101:  889:  582:where 448:for a 222:P = NP 87:Tardos 83:Shmoys 67:P ≠ NP 4624:Dinic 4532:Graph 3851:S2CID 3803:(PDF) 3746:S2CID 3705:S2CID 3621:S2CID 3521:arXiv 3461:S2CID 3408:S2CID 3363:S2CID 3141:n ≄ N 2756:min: 2456:max: 1657:that 1415:tight 1052:) of 4590:SPFA 4558:Prim 4152:and 3985:and 3963:ISBN 3936:ISBN 3916:ISBN 3881:ISBN 3736:ISBN 3695:ISBN 3613:ISSN 3572:ISSN 3453:ISSN 3398:ISBN 3355:ISSN 3314:link 3296:OCLC 3286:ISBN 3179:time 3167:PTAS 3127:and 2266:is: 2014:The 1609:< 1539:> 1048:(or 523:> 358:and 201:> 128:for 89:for 85:and 75:both 42:are 34:and 4520:cut 4385:and 3843:doi 3728:doi 3687:doi 3652:doi 3603:doi 3562:doi 3531:doi 3492:doi 3445:doi 3390:doi 3347:doi 3183:APX 3177:FPT 2295:inf 2128:inf 2094:on 1972:). 1936:of 1799:max 1757:x,y 1646:or 1081:if 491:log 396:by 112:or 30:In 4737:: 4036:, 4032:: 3989:, 3961:, 3957:, 3949:; 3908:. 3900:, 3896:, 3849:. 3841:. 3829:48 3827:. 3823:. 3782:^ 3758:^ 3744:. 3734:. 3703:. 3693:. 3685:. 3646:. 3642:. 3619:. 3611:. 3599:45 3597:. 3593:. 3570:. 3558:43 3556:. 3552:. 3529:. 3517:81 3515:. 3488:74 3482:. 3459:. 3451:. 3443:. 3431:42 3429:. 3406:. 3396:. 3384:. 3361:. 3353:. 3345:. 3333:46 3331:. 3310:}} 3306:{{ 3294:. 3270:^ 3115:∓ 3100:. 1751:, 1612:1. 836:, 538:. 354:, 350:, 81:, 38:, 4518:/ 4022:e 4015:t 4008:v 3995:. 3889:. 3857:. 3845:: 3805:. 3776:. 3752:. 3730:: 3711:. 3689:: 3660:. 3654:: 3648:9 3627:. 3605:: 3578:. 3564:: 3537:. 3533:: 3523:: 3500:. 3494:: 3467:. 3447:: 3414:. 3392:: 3369:. 3349:: 3316:) 3302:. 3257:) 3251:( 3246:) 3242:( 3228:. 3149:c 3137:k 3133:N 3129:k 3125:c 3121:c 3117:k 3113:c 3109:n 3105:n 3094:c 3082:c 3078:c 3074:c 3050:c 3047:+ 3043:T 3040:P 3037:O 3014:T 3011:S 3008:R 3005:O 3002:W 2998:c 2995:+ 2991:T 2988:P 2985:O 2979:1 2972:) 2968:c 2962:1 2959:( 2937:T 2934:P 2931:O 2925:1 2918:) 2914:c 2908:1 2905:( 2883:T 2880:P 2877:O 2873:) 2870:c 2867:+ 2864:1 2861:( 2839:T 2836:P 2833:O 2807:T 2804:P 2801:O 2797:r 2773:) 2770:x 2767:( 2764:f 2740:c 2733:T 2730:P 2727:O 2704:T 2701:S 2698:R 2695:O 2692:W 2688:c 2685:+ 2681:T 2678:P 2675:O 2671:) 2668:c 2662:1 2659:( 2637:T 2634:P 2631:O 2627:) 2624:c 2618:1 2615:( 2593:T 2590:P 2587:O 2583:) 2580:c 2574:1 2571:( 2549:T 2546:P 2543:O 2517:T 2514:P 2511:O 2505:1 2498:r 2473:) 2470:x 2467:( 2464:f 2437:ρ 2431:r 2417:n 2396:. 2393:} 2390:n 2383:| 2379:x 2375:| 2371:, 2368:x 2362:, 2359:r 2353:) 2350:x 2347:( 2342:A 2338:R 2334:, 2329:+ 2324:Z 2316:n 2307:1 2301:r 2298:{ 2292:= 2282:A 2278:R 2247:A 2243:R 2229:r 2213:A 2208:P 2183:. 2180:} 2177:x 2171:, 2168:r 2162:) 2159:x 2156:( 2151:A 2147:R 2140:1 2134:r 2131:{ 2125:= 2120:A 2115:P 2100:x 2096:x 2092:A 2078:) 2075:x 2072:( 2067:A 2063:R 2052:x 2048:A 2032:A 2027:P 1997:1 1986:= 1983:r 1970:n 1968:( 1966:r 1960:- 1958:) 1956:n 1954:( 1950:n 1948:( 1946:r 1942:n 1940:( 1938:r 1930:n 1928:( 1926:r 1922:A 1918:n 1916:( 1914:r 1910:A 1906:y 1902:x 1898:y 1894:y 1892:( 1890:f 1873:, 1869:) 1862:T 1859:P 1856:O 1851:) 1848:y 1845:( 1842:f 1836:, 1830:) 1827:y 1824:( 1821:f 1816:T 1813:P 1810:O 1803:( 1796:= 1793:) 1790:y 1787:, 1784:x 1781:( 1778:R 1765:x 1761:y 1755:( 1753:R 1732:. 1729:) 1726:c 1723:+ 1719:T 1716:P 1713:O 1709:( 1703:) 1700:x 1697:( 1694:f 1688:) 1685:c 1678:T 1675:P 1672:O 1668:( 1655:x 1651:c 1636:ρ 1595:, 1591:T 1588:P 1585:O 1578:) 1575:x 1572:( 1569:f 1562:T 1559:P 1556:O 1545:; 1542:1 1525:, 1521:T 1518:P 1515:O 1505:) 1502:x 1499:( 1496:f 1489:T 1486:P 1483:O 1476:{ 1461:ρ 1457:x 1453:x 1451:( 1449:A 1445:x 1443:( 1441:f 1437:A 1432:ρ 1417:( 1409:; 1397:) 1394:n 1391:( 1368:) 1365:n 1362:( 1350:) 1347:) 1344:i 1341:( 1332:A 1328:( 1325:c 1320:) 1317:) 1314:i 1311:( 1302:s 1298:( 1295:c 1277:; 1265:) 1262:n 1259:( 1236:) 1233:n 1230:( 1218:) 1215:) 1212:i 1209:( 1200:s 1196:( 1193:c 1188:) 1185:) 1182:i 1179:( 1170:A 1166:( 1163:c 1132:n 1129:= 1125:| 1121:i 1117:| 1113:. 1110:t 1107:. 1104:s 1098:I 1092:i 1069:) 1066:n 1063:( 1030:i 1026:S 1019:) 1016:i 1013:( 1004:A 974:s 967:s 947:) 944:i 941:( 938:S 932:s 910:) 907:) 904:i 901:( 898:S 895:( 892:c 886:x 883:a 880:m 876:/ 872:n 869:i 866:m 863:= 860:) 851:s 847:( 844:c 824:) 821:i 818:( 815:S 803:s 774:s 748:s 740:i 737:: 734:S 728:s 724:= 721:) 718:i 715:( 712:S 709:, 706:I 700:i 671:+ 666:R 658:S 655:: 652:c 630:S 610:I 568:S 562:I 559:: 526:0 500:) 497:n 488:n 485:( 482:O 459:+ 456:1 434:) 427:/ 423:1 420:( 417:O 413:n 380:/ 262:) 204:0 175:+ 172:1 20:)

Index

Approximability
computer science
operations research
efficient
algorithms
approximate
optimization problems
NP-hard
theoretical computer science
P ≠ NP
polynomial time
Lenstra
Shmoys
Tardos
scheduling
analysis
mathematical proof
heuristics
annealing
genetic algorithms
theoretical computer science
Goemans–Williamson algorithm
maximum cut
minimum vertex cover
matching
constant-factor approximation algorithm
unique games conjecture
knapsack problem
polynomial-time approximation scheme
P = NP

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